Thanks for asking about this @Ana and sharing a reply @bonnyag! I'll go ahead and put this topic into our External Apps category which we can use for questions/answers about Portals and Embed 
So this part about Portals users is correct!
> each of your portal users has to sign up as retool end-users meaning you’d pay for them like you would pay for any other end-user. Since Retool Portals only works on Business plans or upwards, the pricing for portal users would start at $15/month/user.
But for this part:
>However, if I understand it right, users of embedded apps don’t count as retool end users since you have to manager authentication instead of retool. So if you’re willing to deal with a bit more complexity you might be able to save a few bucks.
Embed users will also be counted as end users, which is mentioned in this doc: https://docs.retool.com/apps/external/quickstarts/embed#3-create-an-embed-url
Still, if this is a blocker, you can always speak with our team to discuss custom pricing that aligns better with your business. We’re happy to help!